Device and method for joining the faces of parts

ABSTRACT

Device for joining faces of parts having great longitudinal extension by friction welding. The device includes first and second clamping arrangements structured and arranged to position ends of the parts against one another. At least one of the first and second clamping arrangements is axially movable with respect to another of the first and second clamping arrangements. At least one of the first and second clamping arrangements is movable along a direction that is parallel to a part cross-sectional plane defined by an end face of one of the parts.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No.10/804,132 filed Mar. 19, 2004, now U.S. Pat. No. 7,469,813, thedisclosure of which is expressly incorporated by reference herein in itsentirety. The instant application also claims priority under 35 U.S.C.§119 of Austrian Application No. A455/2003 filed on Mar. 21, 2003, thedisclosure of which is expressly incorporated by reference herein in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a device and a method for joining the faces ofparts with great longitudinal extension by friction welding. Inparticular, the invention relates to a device and a method for theaxially aligned joining of rails and the like by friction welding.

2. Description of the Prior Art

Joining by welding is characterized according to DIN 1910 in that thecohesion of the parts is achieved through material fusion with the useof heat and/or force. The parting line between the workpieces iseliminated through the metallic bonding of their materials.

In friction welding, the surfaces of the workpieces or parts to bejoined are moved relative to one another under pressure and the surfaceareas are heated through the friction, after which a positioning orpressing of the parts against one another occurs with metallic bondingof the same.

By means of friction welding chiefly parts having a rotationallysymmetrical shape can be joined to one another or attached toworkpieces, whereby at least one part is rotated about its axis, thusmoved relative to the opposite part, and is positioned against a furtherpart or workpiece under pressure. Through the frictional heat releasedat the positioning surfaces, a heating of the surface areas occurs to atemperature at which the material of the part begins to soften. Theactual welding results during the resting of the part(s) and anincreased pressing of the positioning surfaces, a so-called bearingpressure, to obtain a secure metallic bonding of the materials.

Friction welded joints and devices for their production can have greatimportance and be very cost-effective for special materials and ajoining of small or compact parts with a short time-consumption;however, with rods and the like with great longitudinal extension, arotational movement of the same for the friction heating of the jointareas is often possible only with the greatest effort and, in manycases, only theoretically possible.

In particular, with long rods with profiled cross section, such as,e.g., rails or beams, an axially aligned joining with alignment of thecross-sectional profile through friction welding does not seemcost-effective and cannot be produced with a necessary joint quality.

A method for joining railway tracks by friction welding is known from DE198 07 457 A1 in which an intermediate piece is moved in linear ororbital oscillation between the rail ends to be connected. The two railends are thereby pressed toward one another onto the intermediate piecein the longitudinal direction of the rail in order to generate the heatnecessary for welding through friction energy on both contact surfacesbetween each of the rail ends and each of the cut surfaces of theintermediate piece.

However, such a rail joint, which is expensive to produce, results inrespectively two weld transitions that result in an increase ofpotential weak points that will possibly need to be tested extensively.Furthermore, guiding the temperature in the joint area during frictionwelding as well as system-dependent functional operations can be moredifficult to control while maintaining quality.

SUMMARY OF THE INVENTION

The invention provides for a device of the type mentioned at the outsetwith which long rods with profiled cross section, such as rails, can bejoined to one another by friction welding in a rail production, wherebyan axially aligned alignment and a cross-sectionally conformal,high-quality, metallic joining of the parts can be achieved.

The invention also provides for a generic method for the frictionwelding of rods, in particular rails, with which method an all-over,homogenous, cross-sectionally conformal, metallic joining of the endscan be achieved with a high quality of the joint area.

The invention also provides for a friction welding device which featuresclamping arrangements for positioning the part ends against one another.At least one clamping arrangement can be moved relative to the oppositeone, and parallel to the part cross-sectional plane in an axiallydivergent manner. The at least one clamping arrangement can bepositioned in an axially aligned manner to the part with freedom ofmovement.

The advantages obtained with the invention are essentially that thefunctions necessary for a friction welding of the parts with highquality can be adjusted in a precisely controlled manner.Cross-sectionally conformal friction weld joints of, e.g., rails, canthus be produced, whereby only one easily removable lateral elevation ofsmall dimension is formed in the weld area.

If, as can be provided according to the invention, at least one clampingarrangement can be moved in a circulating manner around the joint axis,a favorable homogenous heating of the part ends can result over theentire cross-sectional area.

According to one embodiment of the invention, it is advantageous if bothclamping arrangements can be moved in the same direction in acirculating manner around the joint axis at a respectively oppositespacing from the same. This embodiment of the device renders possible onthe one hand a homogenous heating of the provided joint area of theparts through friction with largely shockless movement operations thatare favorable in terms of mechanical engineering; on the other hand animmediate axially aligned positioning of the part ends with freedom ofmovement is advantageously possible for the actual joining operationthrough eliminating the deflection.

Both with regard to a movement that is as shockless as possible and forthe sake of a quick way of adjusting the part ends to be welded, it isfavorable if a drivable eccentric arrangement that can be adjusted inthe divergence from the rotational axis is provided for the movement andfor the axially aligned resting position of a clamping arrangement.

A particular advantage in connection with the movement operations isobtained if two drivable eccentric arrangements are provided perclamping arrangement and operatively connected to it.

An embodiment of the device according to the invention in which theopposite clamping arrangement respectively can be driven by adjustableeccentric arrangements positioned on a shaft or can be adjusted withfreedom of movement, whereby a divergence from the rotational axispreferably in the opposite direction and an axially aligned alignment ofthe part ends are provided by a control of the eccentric arrangementsthat preferably acts simultaneously, does not only have advantages interms of control technology but also renders possible a constructionmethod that is favorable in terms of cost-effectiveness and industrialengineering.

The invention also provides for a method of the type mentioned at theoutset in that the part ends are provided with flat axially normalcross-sectional surfaces, and subsequently in a heat-up step thecross-sectional surfaces to be joined are pressed against one anotherand at least one part end is moved in an axially divergent mannerrelative to the opposite one and in this manner the face areas arebrought to an increased temperature or joining temperature, at which anaxially aligned alignment of the parts takes place with free movement ofthe same and the weld area is placed under increased pressure for theall-over metallic bonding of the part ends.

The advantages of a welding process conducted in this manner are mainlythat the friction movement occurs without a rotation of the parts and sono high forces of gravity arise with a change in movement of the same.At least one part end is thereby moved in an oscillating manner relativeto the opposite one under pressing pressure in a direction that lies inthe cross-sectional plane. After the joint parameters have been achievedon the friction surfaces, only low forces are necessary for the end-sidefree movement of the parts in order to conduct a cross-sectionallyconformal positioning of the same. If one part end is moved in thecross-sectional plane with elastic bending of the part end area in afavorable manner for friction heating, the restoring forces lead or atleast help to establish an axially aligned alignment of the parts forthe bearing pressure, whereby a single high-quality metallic bond canthus be achieved.

For a largely shockless sequence of movements, it has proven favorablefor at least one part end to be moved in a circulating manner toincrease the temperature or to adjust the joint temperature of the faceareas of the parts.

In a particularly preferred embodiment of the invention, if the partends under pressurization are moved around the alignment or joint axisin the same direction in a circulating manner at an opposite spacingrespectively to the axis to increase the temperature of the face areasof the parts, good all-over weld joints can be achieved in a highlyeffective manner with furthermore reduced shocks in the system, and therespective movements of the part end areas can be reduced. Theexpenditure for a free movement of the part ends is thus also reduced interms of industrial engineering.

For an axially aligned alignment of parts with special cross-sectionalformats provided in the joint process, followed by a welding with thehighest quality, it can be advantageous if, after the pressing togetherof the cross-sectional surfaces and the axially divergent movement ofthe part ends to heat them, the pressing force is reduced, an axialalignment of the parts is carried out and subsequently an increasedpressing pressure is built up for the metallic bonding of the same.

Parts, such as rails of hardenable steels and alloys, can have areaswith an unfavorable, brittle microstructure in the welding joint and/orin the heat-affected zone when a joint is produced by friction welding.This structure, e.g., martensite structure, develops when the materialaustenitizes during welding, i.e., is converted into a cubicface-centered atomic structure, and, after the joining of the parts, thecooling rate, in particular a thermal dissipation in the part, is sogreat that the structural transformation takes place in a suddenlydiffusionless manner. According to the invention this disadvantage canbe overcome in that a pre-heating of the face surface areas of the partends takes place before the heating step.

A pre-heating of the face surface areas of the part ends can be carriedout with particular advantage through relative movement of the sametowards one another with reduced positioning pressure, whereby on theone hand the welding device can thereby be used in a favorable mannerfor heating the part ends and an oxidation of the welding surfaces canbe prevented.

The invention also provides for a device for joining faces of partshaving great longitudinal extension by friction welding, wherein thedevice comprises first and second clamping arrangements structured andarranged to position ends of the parts against one another. At least oneof the first and second clamping arrangements is axially movable withrespect to another of the first and second clamping arrangements. Atleast one of the first and second clamping arrangements is movable alonga direction that is parallel to a part cross-sectional plane, wherebythe part cross-sectional plane is define by an end face of one of theparts.

The first and second clamping arrangements may be structured andarranged to axially aligned the parts. The parts may comprise rodshaving a profiled cross section. The rods may comprise rails. At leastone of the first and second clamping arrangements may be movable in acirculating manner around a joint axis. The first and second clampingarrangements may be movable in the same direction in a circulatingmanner around a joint axis. The first and second clamping arrangementsmay be movable in the same direction in a circulating manner around ajoint axis and while having an opposite spacing.

The device may further comprise first and second drivable eccentricarrangements. The first and second drivable eccentric arrangements maybe movably adjustable. The first and second drivable eccentricarrangements may be structured and arranged to axially aligned the firstand second clamping arrangements. The first and second drivableeccentric arrangements may be structured and arranged to axially alignedthe first and second clamping arrangements in a resting position.

The device may further comprise two drivable eccentric arrangements,wherein at least one of the two drivable eccentric arrangements isoperatively connected to at least one of the first and second clampingarrangements.

The device may further comprise at least one adjustable eccentricarrangement driving one of the first and second clamping arrangements.The at least one adjustable eccentric arrangement may be one ofpositioned on a shaft adjustable with freedom of movement.

The device may further comprise at least one device for controlling theat least one adjustable eccentric arrangement.

The device may further comprise first and second adjustable eccentricarrangements driving the first and second clamping arrangements.

The device may further comprise first and second control devices forcontrolling the first and second adjustable eccentric arrangements.

The first and second adjustable eccentric arrangements may functionsimultaneously.

The invention also provides for a method for joining parts having greatlongitudinal extension by friction welding using the device describedabove wherein the method comprises arranging ends of the parts oppositeone another, wherein the ends are provided with flat axially normalcross-sectional surfaces, pressing the cross-sectional surfaces againstone another by moving at least one of the ends axially relative toanother of the ends, such that face areas of the ends are brought to oneof an increased temperature or a joining temperature, and axiallyaligning the parts, wherein the pressing produces a metallic bonding ofthe parts.

The invention also provides for a method for joining parts having greatlongitudinal extension by friction welding, wherein the method comprisesarranging ends of the parts opposite one another, wherein the ends areprovided with flat axially normal cross-sectional surfaces, pressing thecross-sectional surfaces against one another by moving at least one ofthe ends axially relative to another of the ends, such that face areasof the ends are brought to one of an increased temperature or a joiningtemperature, and axially aligning the parts, wherein the pressingproduces a metallic bonding of the parts.

The pressing may produce an all-over metallic bonding of the ends of theparts. The pressing may produce weld area and takes place underincreased pressure. The parts may comprise rods having a profiled crosssection. The rods may comprise rails.

The method may further comprise moving the end of at least one of theparts in a circulating manner to one of increase a temperature andadjust a joint temperature.

The method may further comprise moving the end of at least one of theparts in a circulating manner to adjust a temperature of a joint,whereby the joint is formed between face areas of the ends of the parts.

The method may further comprise moving the ends of the parts relative toa joint axis to cause in increase in temperature.

The method may further comprise moving the ends of the parts around ajoint axis.

The method may further comprise moving the ends of the parts in the samedirection around a joint axis.

The method may further comprise moving the ends of the parts around ajoint axis in a circulating manner.

The method may further comprise moving the ends of the parts relative toan alignment axis to cause an increase in temperature.

The method may further comprise moving the ends of the parts around analignment axis.

The method may further comprise moving the ends of the parts in the samedirection around an alignment axis.

The method may further comprise moving the ends of the parts around analignment axis in a circulating manner.

The method may further comprise, after the pressing and before theaxially aligning, reducing a pressing force. The method may furthercomprise, after the reducing, increasing a pressing pressure.

The method may further comprise, before the pressing, pre-heating theends of the parts.

The method may further comprise, before the pressing, moving the endsrelative to each other with a reduced positioning pressure, whereby themoving causes pre-heating of the ends of the parts.

The invention also provides for a device for friction welding parts,wherein the device comprises first and second clamping arrangementsstructured and arranged to position ends of the parts against oneanother. At least one of the first and second clamping arrangements isaxially movable with respect to another of the first and second clampingarrangements. First and second moving devices are provided forrespectively moving the first and second clamping arrangements along adirection that is parallel to a part cross-sectional plane. First andsecond control devices are provided for controlling movement of thefirst and second moving devices. The part cross-sectional plane isdefine by an end face of one of the parts.

The invention also provides for a method for joining two parts byfriction welding using the device described above wherein the methodcomprises arranging ends of the two parts opposite one another, pressingthe ends against one another by moving at least one of the ends axiallyrelative to another of the ends, moving the ends relative to each otheralong a direction which is parallel to an end surface of at least one ofthe ends, axially aligning the parts, and metallically bonding the endsof the two parts.

The invention also provides for a device for friction welding parts,wherein the device comprises first and second clamping arrangementsstructured and arranged to position ends of the parts against oneanother. At least one of the first and second clamping arrangements areaxially movable with respect to another of the first and second clampingarrangements. First and second eccentric moving devices are mounted to ashaft. The first and second eccentric moving devices respectively movethe first and second clamping arrangements along a direction that isparallel to an end face of at least one of the parts. A motor drives theshaft. First and second control device are provided for controllingmovement of the first and second eccentric moving devices. The partcross-sectional plane is define by an end face of one of the parts.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in further detail below on the basis of adrawing showing an exemplary embodiment.

The only FIGURE shows in diagrammatic form a friction welding device A.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Clamping arrangements 2, 2′ are provided for parts 1, 1′ to be joined.The first and second clamping arrangements are detachably connected tothe part ends 11, 11′ by clamp parts 21, 21′. The clamping arrangements2, 2′ are operatively connected to at least respectively one adjustableeccentric arrangements 3, 3′ that can be driven by way of a shaft 41 bya motor 4 or the like, whereby the amount of eccentricity can beadjusted through a control 31, 31′ of the eccentric arrangements 3, 3′.

If the eccentric arrangements 3, 3′ are now driven in a rotary manner bya motor 4 via a shaft 41 and their eccentricity is adjusted by controlmeans 31, 31′ in different directions, in particular in oppositedirections, an uneven, in particular opposite, oscillation of therespective eccentric surfaces occurs in the direction towards the partends 11, 11′ to be welded. However, the eccentric arrangements 3, 3′ areoperatively connected to the clamping arrangements 2, 2′, if necessaryvia bearings 5, 5′, and consequently the part ends 11, 11′ clamped inthem can be moved relative to one another. Another support (not shown)of the clamping arrangements 2, 2′ can be carried out via moveablebearings or eccentric arrangements if necessary driven at the sameangular velocity. During a friction welding process parts 1, 1′ to bejoined with their part ends 11, 11′ are clamped with axially normal flatcross-sectional surfaces 12, 12′ in clamping arrangements 2, 2′ by clampparts 21, 21′ and positioned against one another with a force oropposing force +x1,−x1. A relative or friction movement occurs at thepart cross-sectional surfaces 12, 12′ between the opposite part ends 11,11′ during the action of a positioning force through an uneven axiallydivergent movement of the clamping arrangements 2, 2′. Such a relativemovement of the clamping arrangements 2, 2′ is caused by an unevenadjustment of the eccentricity of the eccentric arrangement 3operatively connected to them, which eccentric arrangements are drivenon a shaft 41 in front of a motor 4.

A relative movement during positioning of the cross-sectional surfaces12, 12′ against one another releases friction heating that heats thecross-sectional surface areas to a joint temperature. After such atemperature is reached, a canceling of the eccentricity of the eccentricarrangements 3, 3′ occurs directly and simultaneously through a control31, 31′, and through this an axially aligned free movement of the partends with a subsequent pressurization or force +x2,−x2 of thecross-sectional surfaces 12, 12′.

After a cooling of the formed welding zone of the parts, if necessarywith a reduced cooling rate effected by a pre-heating of the part ends11, 11′ to adjust specific material properties in this area, a materialcrushing effected by a last pressurization or a bearing pressure can bemechanically removed and a profile-conformal joint can thus be achieved.

1. A friction welding device for joining faces of long parts by frictionwelding, wherein a long part is defined as a part comprising an end, anopposite end, a profiled cross-section, and a length which is greaterthan an overall width of the profiled cross-section, the devicecomprising: first and second clamping arrangements structured andarranged to position the ends of the long parts against one another; atleast one of the first and second clamping arrangements being axiallymovable with respect to another of the first and second clampingarrangements; and each of the first and second clamping arrangementsbeing movable along a direction that is parallel to a partcross-sectional plane defined by an end face of one of the long parts.2. The device of claim 1, wherein the first and second clampingarrangements are structured and arranged to axially align the longparts.
 3. The device of claim 1, wherein the long parts comprise rods.4. The device of claim 3, wherein the rods comprise rails.
 5. The deviceof claim 1, wherein at least one of the first and second clampingarrangements is movable in a circulating manner around a joint axis. 6.The device of claim 1, wherein the first and second clampingarrangements are movable in the same direction in a circulating manneraround a joint axis.
 7. The device of claim 1, wherein the first andsecond clamping arrangements are movable in the same direction in acirculating manner around a joint axis and while having an oppositespacing.
 8. The device of claim 1, further comprising first and seconddrivable eccentric arrangements.
 9. The device of claim 8, whereinmovement along the direction parallel to the part cross-sectional planeis movably adjustable by the first and second drivable eccentricarrangements.
 10. The device of claim 8, wherein the first and seconddrivable eccentric arrangements are structured and arranged to axiallyalign the first and second clamping arrangements.
 11. The device ofclaim 8, wherein the first and second drivable eccentric arrangementsare structured and arranged to axially align the first and secondclamping arrangements in a resting position.
 12. The device of claim 1,further comprising two drivable eccentric arrangements, wherein the twodrivable eccentric arrangements is operatively connected to at least oneof the first and second clamping arrangements.
 13. The device of claim1, further comprising at least one adjustable eccentric arrangementdriving one of the first and second clamping arrangements.
 14. Thedevice of claim 13, wherein the at least one adjustable eccentricarrangement is one of positioned on a shaft adjustable with freedom ofmovement.
 15. The device of claim 13, further comprising at least onedevice for controlling the at least one adjustable eccentricarrangement.
 16. The device of claim 1, further comprising first andsecond adjustable eccentric arrangements driving the first and secondclamping arrangements one of in the same direction and in an oppositedirection.
 17. The device of claim 16, further comprising first andsecond control devices for controlling the first and second adjustableeccentric arrangements.
 18. The device of claim 16, wherein the firstand second adjustable eccentric arrangements function simultaneously.19. A friction welding device for friction welding long parts, wherein along part is defined as a part comprising an end, an opposite end, aprofiled cross-section, and a length which is greater than an overallwidth of the profiled cross-section, the device comprising: first andsecond clamping arrangements structured and arranged to position theends of the long parts against one another; at least one of the firstand second clamping arrangements being axially movable with respect toanother of the first and second clamping arrangements; first and secondmoving devices for respectively moving the first and second clampingarrangements along a direction that is parallel to a partcross-sectional plane; and first and second control devices forcontrolling movement of the first and second moving devices, wherein thepart cross-sectional plane is define by an end face of one of the parts.20. A friction welding device for friction welding long parts, wherein along part is defined as a part comprising an end, an opposite end, aprofiled cross-section, and a length which is greater than an overallwidth of the profiled cross-section, the device comprising: first andsecond clamping arrangements structured and arranged to position theends of the long parts against one another; at least one of the firstand second clamping arrangements being axially movable with respect toanother of the first and second clamping arrangements; first and secondeccentric moving devices mounted to a shaft; the first and secondeccentric moving devices respectively moving the first and secondclamping arrangements along a direction that is parallel to an end faceof at least one of the parts; a motor driving the shaft; and first andsecond control devices for controlling movement of the first and secondeccentric moving devices, wherein the part cross-sectional plane isdefine by an end face of one of the parts.
 21. A friction welding systemcomprising: first and second long parts, wherein a long part is definedas a part comprising an end, an opposite end, a profiled cross-section,and a length which is greater than an overall width of the profiledcross-section; and a friction welding device comprising: first andsecond clamping arrangements structured and arranged to position theends of the first and second long parts against one another; at leastone of the first and second clamping arrangements being axially movablewith respect to another of the first and second clamping arrangements;and each of the first and second clamping arrangements being movablealong a direction that is parallel to a part cross-sectional planedefined by an end face of one of the first and second long parts. 22.The system of claim 21, wherein the first and second clampingarrangements are structured and arranged to axially align the first andsecond long parts.
 23. The system of claim 21, wherein the first andsecond long parts comprise first and second rods.
 24. The system ofclaim 23, wherein the first and second rods comprise first and secondrails.
 25. The system of claim 21, wherein at least one of the first andsecond clamping arrangements is movable in a circulating manner around ajoint axis.